In the U.S., every year, an average total of 270 buses were involved in fatal crashes. The exact number for the period of 2001 to 2011 is documented by the National Highway Traffic Safety Administration (NHTSA) (8) In the US, new buses on the road are equipped with seat belts, (9) but a significant number of old buses do not provide seatbelts. (10).
In case of a bus accident, involving a frontal crash or a side impact, seatbelts can prevent passengers from being ejected from their seats, and also protect passengers from collisions into the front seat. All these circumstances can cause serious injuries. Seat belt designs can be divided into the two most common versions: Two-point lap belts and three-point lap/shoulder belts. However, they are not equally safe. Lap belts do not offer sufficient safety especially in frontal crashes. In these cases the passenger's head is not protected from hitting the seat in front what may result into head or upper torso injuries. (11) Conversely, three-point seatbelts prevent injuries and ejections (12). A NHTSA safety research has shown that three-point seatbelts can reduce fatalities by up to 77 percent. This result can mainly be traced back to the fact that seat belt prevent ejections of passengers in case of a rollover. (2) Rollover crashes represent the most dangerous scenario. The data from the Fatality Analysis Reporting System Encyclopedia (FARS) shows that for the period of 2000 to 2009, 55 percent of the crashes resulting in fatalities were rollover crashes. Due to the fact that motor coaches are traditionally designed with a luggage storage room underneath the passenger compartment, these vehicles have a relatively high center of gravity. If the bus is occupied by many passengers, it gets even more top heavy. This means that motor coaches are highly exposed to the risk of turning over in a crash (13). Therefore, especially for buses, it is important to install three-point seat belts, to provide high passenger safety. As well as for rollovers, the installation of seat belts significantly increases passenger safety in frontal or side crashes. (2) Statistically three point seat belts safe a live every seven seconds. Therefore the German patent office has declared the invention of the tree point seat belt, made by Volvo in 1959, as one of the eight most important inventions within the last 100 years. (19; 20; 21; 22)
A literature survey of bus and coach incidents has outlined that fatal crashes occur more frequent in rural roads, (11) where motor coaches travel a lot of times. This fact implicates that motor coaches, in contrast to transit buses, definitely need restraint systems to protect passengers in case of an accident.
In Australia, two momentous accidents in 1989 involving motor coaches lead to legislation, making three point seat belts mandatory in the country. Since then, various serious bus accidents have occurred but no fatal or disabling injuries for occupants wearing seat belts have been documented. (14) An example for the efficiency of seatbelts in terms of occupant protection is given: A bus built in 1996 was involved in a collision with a culvert. The impact speed was approximately 85 km/h, which is an equivalent of 52 mph. 47 of the 52 occupants used their seatbelts. Only the unbuckled persons came up with injuries, including fatal injuries for a relief driver who was thrown out of the window and a child sleeping in the aisle. The remaining unbuckled passengers came into collisions with the front seat. (14)
The fact that passengers travelling on buses are not only exposed to the danger of sustaining a trauma by being ejected from their seats, but also could they get hurt by other unrestrained passengers being ejected against them, has to be considered. (14) For motor coaches offering space for approximately 55 passengers, (15) collisions between passengers also poses a significant risk. For this reason the installation of passenger restraint systems is essential.
In a motor coach accident in Tallulah, La. on Oct. 13, 2003, 16 pairs of seats were ripped off the floor. “Passengers [were] trapped among and underneath the seats”.
Even though the previously mentioned studies have shown, that passenger safety can be significantly improved, the National Highway Traffic Safety Administration from the Department of Transportation has decided not to require retrofit seatbelts for motor coaches. (23) The Department of Transportation names the high efforts on reinforcement of the bus structure, as well as the high costs for retrofitting as reasons, why retrofit seat belts are not feasible.
It is estimated that retrofitting a vehicle with lap belts would cost $6,000, if the seat belts can be attached to the vehicle structure without any strengthening needed. If reinforcement is needed, the costs are estimated to be up to $34,000. A retrofit of lap/shoulder seat belts that meets the requirements imposed in FMVSS No. 210 is estimated to cost $40,000 per bus. With 29,325 buses on the road, the occurring costs for the motor carrier industry are expected to be too high. These numbers are highly doubted by Jaqueline Gillan, (13) the vice president of Advocates for Highway and Auto Safety. Advocates for highway and Auto Safety is an alliance with the objective, to make US roads safer. (24) Gillan calls the cost figures given by the motor coach industry “highly inflated and unreliable”. According to Gillan, an “anonymous and undated document” that does not name “the sources of [the] estimates” has been used to lobby against the new safety requirements. In the last few years, a law has been discussed, which prescribes the safety standards for motor coaches. Finally the National Highway Traffic Safety Administration (NHSTA) has decided not to undertake rulemaking on retrofitting motor coaches with seat belts. The reasons that were named for that decision were the estimated costs for the retrofit of seat belts and the fact that there is no existing solution available. Therefore travelling on these old buses is not safe.
Even though it has been heavily discussed, a rule released on 25 Nov. 2013, requires “seat belts for every passenger seating position for all new over-the-road buses” (Page 2 (16)), but does “not [ . . . ] require retrofitting of used buses with seat belts” (page 5 (16)). This rule is called 49 CFR Part 571—Federal Motor Vehicle Safety Standards (FMVSS). The rule has been released by the US Department of Transportation (DOT)—National Highway Traffic Safety Administration (NHTSA). One of the main reasons why the US Department of Transportation has decided not to require retrofitting buses with seat belts is that the estimated costs for that process are about $40,000 per bus, (page 128 (17)) which will probably cause serious economic problems for the bus owners. If it can be proven, that it is possible to provide a solution that will allow retrofitting for about $10,000 per bus, either the US Department of Transportation might change the rule on retrofitting, or bus owners will voluntarily install seat belts in their buses. Both will help to improve passenger safety for people travelling by bus.
Conventional solutions for restraining passengers, such as disclosed in prior art, fail to adequately address the existing problem.
Notably, in addition to seatbelts, even airbags or rigid bars, as known for rollercoaster applications, could take over the task of restraining passengers (note that since a low cost solution is required, air bags can be eliminated from the consideration). Thus, e.g., US Patent Application USPA 20110210598 A1, Restraint System for Vehicle. (25) presents an added rigid bar for upper torso restraint for police applications. Due to the fact that over-road bus trips are likely to last several hours, the design may not be appropriate for bus type applications, since it will negatively affect passenger comfort.
Another example of a restraint system that cannot be categorized as a seat belt, is US Patent 20090079252 A1, Cross-Cross Harness System for Use with Seats. (26) US Patent 20090079252 A1 also retrofits into a seat. The configuration may be very uncommon for people to use, so it will not be considered as a competitor for retrofitting seats with a restraint system. A system that is totally new to the passengers is undesirable, because people should be able to use the restraint system without needing a safety instruction.
The prior art also discloses a number retrofit seat belt options, most of which can be categorized as portable seatbelts. U.S. Pat. No. 8,371,656 B2, Portable Safety Belt (27), is an example of a design with a seat mounted seat belt assembly. The seat belt assembly consists of a single strap that can be mounted to the back rest of an existing seat, and at the same time be used as a lap belt. (27). U.S. Pat. No. 5,624,135 A, Portable Seat Belt (29), also discloses a portable seatbelt for retrofitting to a certain seat design. The portable seat belt consists of a system of straps that can be wrapped around the backrest of a bus seat and strap up a person safely to the seat. A further example of a portable seatbelts is disclosed in US Patent 20080246265 A1, Over-the shoulder seatbelt. (30) This portable seatbelt design enables the seatbelt to be carried around by the passenger. One disadvantage of these designs is that in case of an accident, all the forces that act on the restrained passenger are transmitted to the bus floor via the pedestal of the bus seat. Bus seats, however, are generally not designed to withstand these forces. Thus, portable seatbelts present added liability and safety concerns and therefore they adequately address the problem of retrofitting motor coaches in the US. (10)
Other prior art solutions that have been proposed may be categorized as new seats (i.e. for replacing the old seats without seatbelts. For example, German Patent DE 19745634 C2, Passenger seat with seat belt attachment to the column, (31) discloses a new seat design with an integrated seat belt system. The cost of purchasing new seats, however, represents a near prohibitive disadvantage.
Several examples for seat mounted seatbelt systems can be found in the prior art. U.S. Pat. No. 4,632,425 A, Passenger Restraint System, (33) is a design from 1985 that was developed for retrofitting school busses with seatbelts. Additionally U.S. Pat. No. 6,676,219 B1, Passenger Restraint Assembly for School Buses, (34) offers a restraint assembly with three straps that can be attached to the seat frame. In both designs the seat frame is required to absorb the forces during a crash.
In contrast to cars, the availability of anchor points for seat belts in buses is limited. The anchor point for the shoulder strap support in a car is often mounted to the side wall of the vehicle frame. This is not an option for the retrofit design, because especially for aisle seats, anchoring points at the side wall cannot be found. As discussed in the previous section, using parts of the seat as an anchor point, as in U.S. Pat. No. 7,651,134 B2, cannot be considered as an option for retrofit seat belts. Another example of this deficiency is U.S. Pat. No. 6,312,056 B1, Occupant Restraint System with Compartmentalization. It provides a retrofit seatbelt design with the retractors mounted at the bottom of the seat.
German Patent DE 4333463 A1, Motor caravan with a fastening device for safety belts (37) discloses a T-shaped support structure for belt retrofit on a caravan. The design can be considered cumbersome for a motor coach (note that the it is specifically designed for the use for caravans). In particular, structure and mounting of the support will not work for motor coaches.
As noted above, one possible approach to retrofitting motor coaches with seatbelts is to replace the seats with new seats that have integrated seatbelts. Unfortunately, this solution is significantly more expensive than installing a retrofit seatbelt. Thus, as discussed previously, new seats cannot be considered as the solution for retrofitting motor coaches. (10) Finding new seats that are designed to withstand the forces that are applied in crash scenarios is not difficult. A great number of new buses are already equipped with seats that provide seat belts. (9) An example for a replacement seat with an integrated seatbelt is U.S. Pat. No. 5,564,785 A, Seat Frame Assembly for Motor Vehicle.
The use of seatbelts is essential in order to provide passenger safety for motor coaches. Considering the fact that still a significant number of US coaches are not equipped with seatbelts, a compelling need for a retrofit system is created. The prior art, as discussed herein, has not provided an adequate solution that offers a safe and cost efficient retrofit system for motor coaches.
Thus, there exists a need for improved low-cost retrofit seatbelt solutions for motor coaches. Advantageously, passenger safety can be significantly increased by providing a well designed restraint system that is able to prevent the ejection of the passenger in case of an accident. This statement is evidenced by the NHTSA safety research. (2). Bringing the problem to a point, passengers have to be protected from injuries that can occur during accidents.